Trex014

Also, how can you tell of your driveshaft has the 35mm or 40mm bearing without removing it first? The sticker on the driveshaft is gone

I just bought a new to me 2006 chevy 2500hd extended cab short bed with the 6.0l and 2wd, all stock. I need to replace the u joints and driveshaft bearing which is no biggie but I have some questions. 1. My driveshaft bearing carrier has no steel support plate between the bearing and mounting spot. Should this truck have that ~1/2" steel spacer? I only ask because some bearings are sold with that spacer that is currently not on my truck. 2. Is there anything bad about non-greasable u joints? 3. How hard is it to replace the transmission output seal for the 4spd automatic and should I while I'm in there? It's not obviously leaking but has some grease/grime around the output. I'm a big fan of preventative matinence. Thanks RJ